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@einen tetes etretQffire JAMES E. EMERSN, F TRENTON, NEW' JE tSll'Y.

i Letters ,Patent No. 66,692, dated-July 1.6, 1867.

IMPROVEMENT Iii SAWS.

TO ALL WIIOMVIT MAY CONCERN:

Beit ltnown that IJAMES E. EMERSON, ot Trenton, in the county of Mercer,and State of New Jersey, have invented certain new and usefulImprovement i'n Saws; and I do hereby declare the following to be afull, clear, and exact description of the saine, reference being had tothe accompanying drawing, which is made n part of this specification,and which represents u side elevation of a saw-blade, which, for thesalte ol` convenience ot' illustration, has been made to exhibit severalvarieties of teeth.

The lirst part of my invention consists iu providing thc saw withapertures or perforations, a series or plurality of which extendconsecutively and in a definite line from or near the throat or point ofjuncture of each pair of teeth, and which subserve the purpose offacilitating the sharpening ot' the saw, as will be hereinafter morefully explained. The second part' of my invention consists in a novelmethod of forming the saw with clearing-teeth, in connection withchambers or openings in the blade, for the purpose ot' removing thesawdust from the korf, and cutting oi the ridge which remains at thcbase of thekerf in consequence of the set position of the teeth.

In order that others skilled in the art to which my invention appertoinsmay be enabled to fully under stand and use the same, I will proc-eed todescribe itin detail, in connection with the accompanying drawings.

The ligure is a representation of usingle blade, having a set or largeteeth, a, and of small teeth b, such as are formed on the blades ot'crosscut or reciprocating saws, and a circular or Islitting sawtooth, e.It is oi' course to he understood that this embodiment of the severalvarieties of teeth in a single blade is merely to condense theillustration, the individual saws, as manufactured, necessarilyembracing but one hind of workingtooth. d cl d represent apertures,which are punched through the thickness of the blade or otherwiseproduced therein, a plurality of which apertures extend in a definiteline or series from the point of juncture between each pair of teethtoward the back of the saw-blade. 'lhe object and utility of theseapertures will be understood from the following explanation: Under thcmethod ol construction heretofore most commonly adopted, it is necessaryto bring the saw-glimmer into requisition as often as the teeth needsharpening, the operation .of said instrument involving considerabledificulty, and the instrument itself being in many instancesunobtainable. The use of the gummer is rendered necessary, because thetile itself cannet be made to cut with the required precision, or formthe curvature at the throat of the teeth to obviate cracks or fractures.It will be seen that in my case the apertures cl, being taken as aguide, enable the file to be effectively applied with facility. Toenable the metal between the apertures d to be readily removed by thefile, IY propose to soften rhis'part of the blade through the agency ofheat, which may also serve as a medium for toughening the blade in theregion of said apertures. The apertures d may. be made in various forms.In circular saws the apertures d should be disposed in a linecorresponding to the direction 'in which the teeth wear and aresharpened, as shown in the drawing. I am aware that John Lippincottobtained a patent on the thirteenth day et' March, 1866, for a saw inwhich is provided a slot or indentation, having parallel sides, andextending into the blade below the root or termination of the inclinedside of the teeth, for the purpose of servingvas a guide in dressing thesaw with a. tile. y'this method a large portion of metal isrelnoved, andthe teeth are made liable to yield or vibrate, and henceoperate'inetliciently. In my saw each portion of metal between theapertures d adds to the strength and rigidity of the teeth. e erepresent chambers or openings formed at suitable intervals in thesaw-blade, and i extending into the latter from the extreme cutting-edgeto a point considerably beyond the hase of the teeth, said chambersterminating in a curve, to avoid. liability of fracture. These openingsor chambers e divide the teeth into sets of any desired number, as maybe properly eoicuiated in constructing the saw, cach of such sets beingconcluded by a half` tooth,f, the point of which stands out of line withand somewhat nearer the longitudinal centre of the saw than the pointsof the working-teeth. This halt toothf serves not only to remove theridge at the base of the korf, but also clears thc korf of sawdust, anddeposits the same in the chamber c, which carries the dust out of thekort' and drops it. The clearing-toothf has straight or rectilinearsides, so that in dressing the same the relation of its point to thepoints of the working-teeth will always be uniformly mointained. It isalso well braced and steady in operation, from the fact elf beingjoinodnt one side to the section of the saw upon which a set of 'theworking-teeth are formed. I um aware that it is not new to form a hookedclearingftooth on the toothed sections of a saw, euch feature beingexhibited in a withdrawn application, tiled by George R. Atkins, in 1857but iu this oase the clearing-tooth is not susceptible of dressing ertiling without changing the relation between the points' oi' theclearing and working-teeth to such an extent ns to materially impair oraltogether destroy the eliiciency of the saw. K i

Having thus described my invention, what I claim as new hcrein',^anddesire to secure by Letters Patent, is-

The provision in u saw of apertures d, for facilitating dressing orsharpening, substantially as described.v

. J. E. EMERSON.

Witnesses:

Cnas, D. Snrrn, Cms. A. Pnr'rrr.

